I plugged nanoVNA into a MacBook via USB 2.0 hub
and launched
from Chrome, after enabling its webUSB via the first Wiki link.
I suspect that nanoVNA behaves better via USB 2.0 than 3.0...
Web-Client behaves nicely on MacBook Chrome browser..
Chrome on iPad cannot load the Web-Client page,
and I cannot find any serial terminal console app for iOS
to test whether its USB connects to nanoVNA...